1. Technical Field of the Invention
The present model concerns a tool used in the mounting operation of a tyre onto a rim.
2. Prior Art
The mounting of a tyre onto a rim foresees taking the bead of the tyre below the bead-stopping edge in the channel of the rim. This operation is carried out with the help of per se known tyre-dismounting machines, which are equipped with a tool the function of which is to press upon the sidewall of the tyre or upon the bead, whilst the rim is made to rotate, in order to insert the bead into the suitable seat of the rim.
To make this operation easier a tool is known that is described and illustrated in Italian patent application for a utility model no. RE2002U000004 to the same Applicant.
In brief said tool comprising a body equipped with a base (or fixed jaw) and with a mobile jaw to which means are operatively connected suitable for bringing said mobile jaw closer to said fixed jaw to jam the edge of the rim between them so as to lock said body to the edge of the rim. The lower surface of the base, when the tool is fixed to the edge of the rim, presses against the sidewall of the tyre so as to keep the bead of the tyre distanced from the edge of the rim and allow it to slide in the radial direction, during the rotation of the wheel, inside the central channel of the rim. The surface of the tool is shaped in such a way as to promote the sliding thereof.
The tool described above, whilst performing the function for which is intended perfectly well, even when it is used to mount very rigid and large tyres, has proven not very effective in mounting Run Flat tyres, i.e. the type of tyres that allows the vehicle to travel even in conditions of low tyre pressure.
It has been found that during the mounting of these types of tyres, using the device described above, the sidewall of the tyre does not slide with respect to the base of the device, not even if the latter is lubricated, and consequently the bead of the tyre is not easily directed towards the channel of the rim.
This is mainly due to the fact that these tyres have, on the sidewall, a raised band intended to rest on the edge of the rim, said band interfering with the surface of the tool blocking the sliding in the radial direction of the sidewall of the tyre.
This means both difficulty in mounting the tyre and the generation of great tensions on the carcass of the tyre that lead to an undesired weakening of its structure.